Foldable display device

ABSTRACT

A foldable display device includes a display area having a plurality of unit pixels and a non-display area surrounding the display area, and a folding area defined in the display area and the non-display area, and non-folding areas on both sides of the folding area. The foldable display device can further include a first substrate, a second substrate corresponding to the first substrate and including the plurality of unit pixels, a thin film transistor disposed on the second substrate, an organic light emitting diode disposed on the thin film transistor, and a mesh pattern disposed between the first substrate and the second substrate and having a plurality of openings. Openings of the mesh pattern in the folding area are smaller in size than openings of the mesh pattern in the non-folding areas.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No.10-2020-0080641 filed on Jun. 30, 2020, in the Korean IntellectualProperty Office, the entire contents of which are hereby expresslyincorporated herein by reference into the present application.

BACKGROUND Field

The present disclosure relates to a foldable display device in which thevisibility of a pattern portion in a folding area can be improved andthe occurrence of mura in the folding area during driving can beminimized.

Description of the Related Art

Recently, with the advancement of the information age, display devicesfor processing and displaying a large amount of information have beendeveloped. Display devices used for a computer monitor, a TV, a mobilephone, etc. include an organic light emitting display (OLED) that emitslight by itself, a liquid crystal display (LCD) that requires a separatelight source, etc.

As the display devices have been increasingly applied to diverse fields,such as a computer monitor, a TV, and a personal mobile device, displaydevices having a large display area and a reduced volume and weight havebeen studied.

Specially, recently, flexible display devices manufactured to display animage even when bent or folded like paper have received attention as thenext-generation display devices. The flexible display devices can beclassified into an unbreakable display device which has a highdurability by using a thin film transistor substrate made of plasticinstead of glass, and a bendable display device which is capable ofbeing bent without breaking. Also, the flexible display devices can alsobe classified into a rollable display device which is capable of beingrolled, and a foldable display device which is capable of being folded.The flexible display devices are good in space usability, interior, anddesign and can be applied to various application fields.

Meanwhile, the foldable display device needs to be capable of beingfolded and unfolded. Therefore, a pattern portion is formed in a foldingarea of a structure that supports a display panel to secure flexibility,but while the foldable display device is not driven, the pattern portioncan be seen from the outside. Also, heat generated while the foldabledisplay device is driven may not be uniformly diffused in the foldingarea. Therefore, mura may occur due to a temperature difference, whichcauses degradation in display quality of the foldable display device.

SUMMARY OF THE INVENTION

An object to be achieved by the present disclosure is to provide afoldable display device in which the visibility of a pattern portion ofa structure that supports a display panel can be improved.

Another object to be achieved by the present disclosure is to provide afoldable display device in which the occurrence of mura in a foldingarea during driving of the display device can be suppressed.

Objects of the present disclosure are not limited to the above-mentionedobjects, and other objects, which are not mentioned above, can beclearly understood by those skilled in the art from the followingdescriptions.

According to an aspect of the present disclosure, the foldable displaydevice includes a display area having a plurality of unit pixels and anon-display area surrounding the display area. The foldable displaydevice further includes a folding area defined in the display area andthe non-display area and non-folding areas on both sides of the foldingarea. The foldable display device includes a first substrate; a secondsubstrate corresponding to the first substrate and having the pluralityof unit pixels; and a thin film transistor disposed on the secondsubstrate. The foldable display device further includes an organic lightemitting diode disposed on the thin film transistor; and a mesh patterndisposed between the first substrate and the second substrate andincluding a plurality of openings. Openings of the mesh pattern in thefolding area can be smaller in size than openings of the mesh pattern inthe non-folding areas. For example, the foldable display deviceaccording to an exemplary embodiment of the present disclosure includesthe mesh pattern made of metal and having the plurality of openingsbetween the flexible substrates. Further, the openings of the meshpattern increase in size from the folding area toward the non-foldingareas. Therefore, the visibility of a pattern portion of a structurethat supports a display panel can be improved, and the occurrence ofmura in the folding area can be suppressed.

According to another aspect of the present disclosure, the foldabledisplay device includes a folding area and a non-folding area. Thefoldable display device includes a support substrate having an openingpattern corresponding to the folding area; and a first substratedisposed on the support substrate. The foldable display device furtherincludes a second substrate disposed on the first substrate andincluding a thin film transistor and an organic light emitting diode;and a mesh pattern disposed between the first substrate and the secondsubstrate and having a plurality of openings. A line width of the meshpattern in a folding boundary area between the folding area and thenon-folding area can be smaller than a line width of the wiring line ofthe mesh pattern in the folding area and greater than a line width ofthe wiring line of the mesh pattern in the non-folding area.

Other detailed matters of the exemplary embodiments are included in thedetailed description and the drawings.

According to the present disclosure, a foldable display device includesa mesh pattern made of metal and having a plurality of openings betweenflexible substrates. Further, the openings of the mesh pattern increasein size from a folding area to non-folding areas. Therefore, thereflectivity at a pattern portion of a structure that supports a displaypanel can be reduced, and, thus, it is possible to minimize visualrecognition of the pattern portion.

Further, according to the present disclosure, heat generated from adisplay panel while a foldable display device is driven can be easilydiffused, and, thus, it is possible to suppress the occurrence of murain a folding area.

The effects and advantages of the present disclosure are not limited tothe above-described effects and advantages. Although not describedherein, other effects and advantages of the present disclosure can beclearly understood by a person with ordinary skill in the art from thefollowing descriptions.

The effects and advantages according to the present disclosure are notlimited to the contents exemplified above, and more various effects andadvantages are included in the present specification.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a plan view of a foldable display device according to anexemplary embodiment of the present disclosure;

FIG. 2 is a cross-sectional view of the foldable display deviceaccording to an exemplary embodiment of the present disclosure;

FIG. 3 is a cross-sectional view of a display panel of the foldabledisplay device according to an exemplary embodiment of the presentdisclosure;

FIG. 4 is a diagram illustrating a structure of a support substrate ofthe foldable display device according to an exemplary embodiment of thepresent disclosure;

FIG. 5 illustrates a structure of a unit pixel and a mesh pattern of thefoldable display device according to an exemplary embodiment of thepresent disclosure;

FIG. 6 illustrates a structure of a unit pixel and a mesh pattern of afoldable display device according to another exemplary embodiment of thepresent disclosure;

FIG. 7 is a plan view of a foldable display device according to yetanother exemplary embodiment of the present disclosure;

FIG. 8A through FIG. 8C illustrate a structure of a mesh pattern of thefoldable display device according to yet another exemplary embodiment ofthe present disclosure;

FIG. 9 is a plan view of a foldable display device according to stillanother exemplary embodiment of the present disclosure;

FIG. 10A through FIG. 10C illustrate a detailed structure of a meshpattern of the foldable display device according to still anotherexemplary embodiment of the present disclosure;

FIG. 11 is a plan view of a foldable display device according to stillanother exemplary embodiment of the present disclosure;

FIG. 12 is a diagram illustrating a structure of a support substrate ofthe foldable display device according to still another exemplaryembodiment of the present disclosure; and

FIG. 13 is a cross-sectional view of the foldable display device whenfolded according to still another exemplary embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Advantages and characteristics of the present disclosure and a method ofachieving the advantages and characteristics will be clear by referringto exemplary embodiments described below in detail together with theaccompanying drawings. However, the present disclosure is not limited tothe exemplary embodiments disclosed herein but will be implemented invarious forms. The exemplary embodiments are provided by way of exampleonly so that those skilled in the art can fully understand thedisclosures of the present disclosure and the scope of the presentdisclosure. Therefore, the present disclosure will be defined only bythe scope of the appended claims.

The shapes, sizes, ratios, angles, numbers, and the like illustrated inthe accompanying drawings for describing the exemplary embodiments ofthe present disclosure are merely examples, and the present disclosureis not limited thereto. Like reference numerals generally denote likeelements throughout the specification. Further, in the followingdescription of the present disclosure, a detailed explanation of knownrelated technologies can be omitted to avoid unnecessarily obscuring thesubject matter of the present disclosure. The terms such as “including,”“having,” and “consist of” used herein are generally intended to allowother components to be added unless the terms are used with the term“only”. Any references to singular can include plural unless expresslystated otherwise.

Components are interpreted to include an ordinary error range even ifnot expressly stated.

When the position relation between two parts is described using theterms such as “on”, “above”, “below”, and “next”, one or more parts canbe positioned between the two parts unless the terms are used with theterm “immediately” or “directly”.

When an element or layer is disposed “on” another element or layer,another layer or another element can be interposed directly on the otherelement or therebetween.

Although the terms “first”, “second”, and the like are used fordescribing various components, these components are not confined bythese terms. These terms are merely used for distinguishing onecomponent from the other components and may not necessarily defineorder. Therefore, a first component to be mentioned below can be asecond component in a technical concept of the present disclosure.

Like reference numerals generally denote like elements throughout thespecification.

A size and a thickness of each component illustrated in the drawing areillustrated for convenience of description, and the present disclosureis not limited to the size and the thickness of the componentillustrated.

The features of various embodiments of the present disclosure can bepartially or entirely adhered to or combined with each other and can beinterlocked and operated in technically various ways, and theembodiments can be carried out independently of or in association witheach other.

Hereinafter, a foldable display device according to exemplaryembodiments of the present disclosure will be described in detail withreference to accompanying drawings.

FIG. 1 is a plan view of a foldable display device according to anexemplary embodiment of the present disclosure. All components of eachfoldable display device according to all embodiments of the presentdisclosure are operatively coupled and configured.

Referring to FIG. 1 , a display panel 100 of a foldable display device1000 according to an exemplary embodiment of the present disclosureincludes a display area DA and a non-display area NDA. Further, thedisplay panel 100 of the foldable display device 1000 according to anexemplary embodiment of the present disclosure includes a folding areaFA, non-folding areas NFA1 and NFA2 except the folding area FA, andfolding boundary areas BA1 and BA2 between the folding area FA and thenon-folding areas NFA1 and NFA2.

More specifically, the display panel 100 refers to any type of a displaysubstrate configured to display an image using a transistor circuit. Thefoldable display device 1000 according to an exemplary embodiment of thepresent disclosure can be implemented as an organic light emittingdisplay, but is not limited thereto. The foldable display device 1000according to an exemplary embodiment of the present disclosure can beapplied to a quantum dot display device, a micro light emitting diode(μ-LED) display device, and the like.

Substrates 111 and 112 on which the display panel 100 of the foldabledisplay device 1000 according to an exemplary embodiment of the presentdisclosure is formed can have flexibility. For example, the substrates111 and 112 can be made of a polymer material, such as polyimide (PI),or a plastic material.

Referring to FIG. 1 , the display area DA is provided on the entiresurface of the display panel 100. The display area DA is configured todisplay an image, and a plurality of sub-pixels SP is disposed in thedisplay area DA.

In the display area DA, sub-pixels SP including emission areas fordisplaying an image and driving circuits for driving the sub-pixels SPcan be disposed. Each sub-pixel SP is configured to display a color, andincludes an emission area EA where light is emitted and a non-emissionarea NEA where light is not emitted.

A plurality of sub-pixels SP in the display area DA can form a pixel P,and a plurality of pixels P each including a plurality of sub-pixels SPcan substantially display an image. Further, a plurality of pixels P canbe disposed adjacent to each other and can form a unit. Therefore, unitpixels UP can be disposed repeatedly inside the display area DA.

The non-display area NDA is disposed outside the display area DA so asto surround the display area DA. For example, the non-display area NDAcan be formed to surround the display area DA. The non-display area NDArefers to an area that does not substantially display an image. In thenon-display area NDA, circuits for supplying driving signals and drivingvoltages to enable the display area DA to display an image are provided.

In the non-display area NDA, various wiring lines, driver ICs, a printedcircuit board and the like for driving the pixels and driving circuitsdisposed in the display area DA are disposed. For example, various ICs,such as a gate driver IC and a data driver IC, and VSS lines can bedisposed in the non-display area NDA.

Referring to FIG. 1 , the folding area FA refers to a folded area whenthe foldable display device 1000 is folded. The display panel 100 can befolded or bent with a specific radius of curvature around a foldingaxis. For example, the folding area FA refers to an area where thedisplay panel 100 can be folded or bent. The folding area FA can includethe display area DA and the non-display area NDA.

The folding area FA can be formed across the display area DA and thenon-display area NDA. When the display panel 100 is folded or bent, thefolding area FA can be formed from one side edge to the other edge ofthe display panel 100. In this case, the folding area FA is extendedfrom an outer boundary of the non-display area NDA and formed acrossfrom one side to the other side of the display area DA.

For example, when a central portion of the display panel 100 is folded,the folding area FA can be formed to span a central portion of thedisplay area DA and the non-display area NDA.

The non-folding areas NFA1 and NFA2 refer to non-folded areas when thefoldable display device 1000 is folded. For example, the non-foldingareas NFA1 and NFA2 maintain a flat state when the foldable displaydevice 1000 is folded. The non-folding areas NFA1 and NFA2 can belocated on both sides of the folding area FA. For example, if a foldingaxis of the folding area FA is formed in a Y-axis direction, thenon-folding areas NFA1 and NFA2 are defined as extending from thefolding area FA in an X-axis direction perpendicular to the foldingaxis. For example, the folding area FA is formed between the twoadjacent non-folding areas NFA1 and NFA2.

When the foldable display device 1000 is folded, the folding area FA isfolded around the folding axis and the folding area FA forms a part of acircle or an oval. Here, the radius of curvature of the folding area FArefers to the radius of the circle or oval formed by the folding areaFA. When the folding area FA is folded around the folding axis, thenon-folding areas NFA1 and NFA2 can overlap each other.

Referring to FIG. 1 , the foldable display device 1000 according to anexemplary embodiment of the present disclosure can include the foldingboundary areas BA1 and BA2 between the folding area FA and thenon-folding areas NFA1 and NFA2. For example, a first folding boundaryarea BA1 is disposed between the folding area FA and the firstnon-folding area NFA1, and a second folding boundary area BA2 isdisposed between the folding area FA and the second non-folding areaNFA2.

A first non-folding area NFA1 and a second non-folding area NFA2 can bedisposed respectively corresponding to both edge areas of an openingpattern 165 formed in a support substrate 160 disposed under the displaypanel 100.

Referring to FIG. 1 , the foldable display device 1000 according to anexemplary embodiment of the present disclosure can include the displayarea DA having unit pixels composed of a plurality of pixels P and thenon-display area NDA surrounding the display area DA. Further, thefoldable display device 1000 can include the folding area FA and thenon-folding areas NFA1 and NFA2 on both sides of the folding area FAdefined in the display area DA and the non-display area NDA.

Further, referring to FIG. 1 , the foldable display device 1000according to an exemplary embodiment of the present disclosure caninclude the folding boundary areas BA1 and BA2 between the folding areaFA and the non-folding areas NFA1 and NFA2. For example, the foldabledisplay device 1000 can include the first folding boundary area BA1between the folding area FA and the first non-folding area NFA1, and thesecond folding boundary area BA2 between the folding area FA and thesecond non-folding area NFA2.

Referring to FIG. 1 , the foldable display device 1000 according to anexemplary embodiment of the present disclosure can include a firstsubstrate 111 on which components of the foldable display panel 100 areformed, and a second substrate 112 disposed on the first substrate 111.A mesh pattern 120 having a plurality of openings OA can be formed onthe first substrate 111. For example, the foldable display device 1000according to an exemplary embodiment of the present disclosure caninclude the mesh pattern 120 having the plurality of openings OA betweenthe first substrate 111 and the second substrate 112.

The mesh pattern 120 of the foldable display device 1000 according to anexemplary embodiment of the present disclosure reduces the reflectivityat a pattern portion 165 formed in the folding area FA of the supportsubstrate 160, which is a structure disposed under the display panel 100and configured to support the display panel 100. Therefore, the meshpattern 120 can function to minimize a user's visual recognition of thepattern portion 165. Further, the mesh pattern 120 can easily diffuseheat generated from the display panel 100 while the foldable displaydevice 1000 is driven. Therefore, the mesh pattern 120 can function tosuppress the occurrence of mura in the folding area FA.

Referring to FIG. 1 , the mesh pattern 120 of the foldable displaydevice 1000 according to an exemplary embodiment of the presentdisclosure is greater in size than the display area DA. Further, themesh pattern 120 is smaller in size than the first substrate 111 or thesecond substrate 112. Thus, the mesh pattern 120 made of a metalmaterial is not exposed to the outside of the first substrate 111 or thesecond substrate 112. Therefore, it is possible to suppress corrosion ofthe mesh pattern 120.

Further, in the foldable display device 1000 according to an exemplaryembodiment of the present disclosure, the openings OA of the meshpattern 120 in the non-display area NDA can be identical in size to theopenings OA of the mesh pattern 120 in the adjacent display area DA.

Referring to FIG. 1 and FIG. 2 , the foldable display device 1000according to an exemplary embodiment of the present disclosure caninclude a plurality of first mesh patterns 120 a having first openingsOA1 in the folding area FA.

Further, referring to FIG. 1 and FIG. 2 , the foldable display device1000 according to an exemplary embodiment of the present disclosure caninclude a plurality of second mesh patterns 120 b having second openingsOA2 in each of the first folding boundary area BA1 and the secondfolding boundary area BA2, which are the folding boundary areas BA1 andBA2. The first folding boundary area BA1 can be formed to have openingsidentical in size to the second opening OA2 in the second foldingboundary area BA2.

Further, referring to FIG. 1 and FIG. 2 , the foldable display device1000 according to an exemplary embodiment of the present disclosure caninclude a plurality of third mesh patterns 120 c having third openingsOA3 in each of the first non-folding area NFA1 and the secondnon-folding area NFA2, which are the non-folding areas NFA1 and NFA2.The first non-folding area NFA1 can be formed to have openings identicalin size to the third opening OA3 in the second non-folding area NFA2.

Referring to FIG. 1 and FIG. 2 , in the foldable display device 1000according to an exemplary embodiment of the present disclosure, theopenings OA1 of the mesh patterns 120 a in the folding area FA can beformed smaller in size than the openings OA3 of the mesh patterns 120 cin the non-folding areas NFA1 and NFA2.

Further, referring to FIG. 1 and FIG. 2 , in the foldable display device1000 according to an exemplary embodiment of the present disclosure, theopenings OA1 of the mesh patterns 120 a in the folding area FA can beformed smaller in size than the openings OA2 of the mesh patterns 120 bin the folding boundary areas BA1 and BA2.

Further, referring to FIG. 1 and FIG. 2 , in the foldable display device1000 according to an exemplary embodiment of the present disclosure, theopenings OA2 of the mesh patterns 120 b in the folding boundary areasBA1 and BA2 can be formed smaller in size than the openings OA3 of themesh patterns 120 c in the non-folding areas NFA1 and NFA2.

For example, in the foldable display device 1000 according to anexemplary embodiment of the present disclosure, the openings OA2 of themesh patterns 120 b in the folding boundary areas BA1 and BA2 can begreater in size than the openings OA1 of the mesh patterns 120 a in thefolding area FA. Further, the openings OA2 of the mesh patterns 120 b inthe folding boundary areas BA1 and BA2 can be smaller in size than theopenings OA3 of the mesh patterns 120 c in the non-folding areas NFA1and NFA2.

FIG. 2 is a cross-sectional view of the foldable display device 1000according to an exemplary embodiment of the present disclosure.

Referring to FIG. 2 , the foldable display device 1000 according to anexemplary embodiment of the present disclosure can include the displaypanel 100 including the first substrate 111 and the second substrate 112which have flexibility and display panel components 105 formed on thesecond substrate 112.

Specifically, in the foldable display device 1000 according to anexemplary embodiment of the present disclosure, the display panel 100includes the first substrate 111 and the second substrate 112, which arevery thin flexible substrates, to achieve flexibility and foldability.The first substrate 111 and the second substrate 112 can be made ofinsulating materials having flexibility. For example, the firstsubstrate 111 and the second substrate 112 can be made of an insulatingplastic selected from polyimide, polyethersulfone, polyethyleneterephthalate and polycarbonate.

Referring to FIG. 2 , the foldable display device 1000 according to anexemplary embodiment of the present disclosure can include the meshpattern 120 having the plurality of openings OA on the first substrate111. For example, the foldable display device 1000 according to anexemplary embodiment of the present disclosure can include the meshpattern 120 having the plurality of openings OA disposed between thefirst substrate 111 and the second substrate 112.

Referring to FIG. 2 , the foldable display device 1000 according to anexemplary embodiment of the present disclosure can include the pluralityof first mesh patterns 120 a having the first openings OA1 in thefolding area FA. The foldable display device 1000 can include theplurality of second mesh patterns 120 b having the second openings OA2in each of the first folding boundary area BA1 and the second foldingboundary area BA2, which are the folding boundary areas BA1 and BA2.Further, the foldable display device 1000 can include the plurality ofthird mesh patterns 120 c having the third openings OA3 in each of thefirst non-folding area NFA1 and the second non-folding area NFA2, whichare the non-folding areas NFA1 and NFA2.

Referring to FIG. 2 , in the foldable display device 1000 according toan exemplary embodiment of the present disclosure, the openings OA1 ofthe mesh patterns 120 a in the folding area FA can be formed smaller insize than the openings OA3 of the mesh patterns 120 c in the non-foldingareas NFA1 and NFA2.

Further, referring to FIG. 2 , in the foldable display device 1000according to an exemplary embodiment of the present disclosure, theopenings OA1 of the mesh patterns 120 a in the folding area FA can beformed smaller in size than the openings OA2 of the mesh patterns 120 bin the folding boundary areas BA1 and BA2.

Further, Referring to FIG. 2 , in the foldable display device 1000according to an exemplary embodiment of the present disclosure, theopenings OA2 of the mesh patterns 120 b in the folding boundary areasBA1 and BA2 can be formed smaller in size than the openings OA3 of themesh patterns 120 c in the non-folding areas NFA1 and NFA2.

Furthermore, referring to FIG. 2 , the display panel 100 can include aninsulating layer 125 between the first substrate 111 and the secondsubstrate 112. The insulating layer 125 can be formed to fully cover themesh pattern 120.

Referring to FIG. 2 , in the foldable display device 1000 according toan exemplary embodiment of the present disclosure, a support structure180 is disposed under the display panel 100. The support structure 180is a plate-type frame configured to protect and support the displaypanel 100. The support structure 180 supports the first substrate 111and the second substrate 112 of the display panel 100 so as not to sag.Further, the support structure 180 protects the components disposed onthe first substrate 111 and the second substrate 112 against moisture,heat, impact, etc. form the outside. The support structure 180 can befixed to the display panel 100 by an adhesive material or the like.

Referring to FIG. 2 , the support structure 180 includes the supportsubstrate 160, a back plate 171, an impact absorption layer 170, a coverwindow 190, a first adhesive layer 175, a second adhesive layer 176 anda third adhesive layer 177.

Referring to FIG. 2 , the foldable display device 1000 according to anexemplary embodiment of the present disclosure includes the firstfolding boundary area BA1 between the folding area FA and the firstnon-folding area NFA1, and the second folding boundary area BA2 betweenthe folding area FA and the second non-folding area NFA2. The firstfolding boundary area BA1 and the second folding boundary area BA2 canbe disposed respectively corresponding to both edge areas of the openingpattern 165 in the support substrate 160.

Referring to FIG. 2 , the back plate 171 is configured to enhance thestrength of the support structure 180 and support the display panel 100together with the support substrate 160, and can be referred to as a topplate. The back plate 171 functions to maintain a constant radius ofcurvature of the display panel 100 while the foldable display device1000 is folded. Further, the back plate 171 functions to suppress theoccurrence of creases on a top surface of the display panel 100. Theback plate 171 is disposed between the support substrate 160 and thedisplay panel 100 and can be made of a transparent organic material.

A polarizing film 185 can be disposed on the display panel 100. Thepolarizing film 185 polarizes light emitted from the display panel 100at a polarization angle. The polarizing film 185 emits the lightpolarized at the polarization angle to the outside. The polarizing film185 can function to suppress reflection of external light except thelight polarized at the polarization angle.

The cover window 190 can be disposed on the polarizing film 185. Thecover window 190 protects the display panel 100 against impact from theoutside. The cover window 190 can be implemented as a foldable flexibleplastic-based cover to achieve thinness and flexibility of the foldabledisplay device 1000.

Referring to FIG. 2 , the first adhesive layer 175 can be disposedbetween the support substrate 160 and the back plate 171, and the secondadhesive layer 176 can be disposed between the back plate 171 and thefirst substrate 111. Further, the third adhesive layer 177 can bedisposed between the display panel 100 and the polarizing film 185.

The first adhesive layer 175 can be uniformly disposed on the entire topsurface of the support substrate 160 to bond the support substrate 160and the back plate 171. Further, the second adhesive layer 176 can beuniformly disposed on the entire top surface of the back plate 171 tobond the back plate 171 and the first substrate 111. Further, the thirdadhesive layer 177 can be uniformly disposed on the entire top surfaceof the display panel 100 to bond the display panel 100 and thepolarizing film 185.

The first adhesive layer 175, the second adhesive layer 176 and thethird adhesive layer 177 can be formed as transparent adhesive layersof, for example, optical clear resin (OCR), optical clear adhesive(OCA), or the like, but are not limited thereto.

FIG. 3 is a cross-sectional view of the display panel 100 of thefoldable display device 1000 according to an exemplary embodiment of thepresent disclosure.

For example, FIG. 3 is a schematic cross-sectional view of twosub-pixels SP of the display panel 100 of the foldable display device1000 according to an exemplary embodiment of the present disclosure.

Referring to FIG. 3 , the second substrate 112 is disposed on the firstsubstrate 111 so as to correspond to the first substrate 111. The secondsubstrate 112 is configured to support various display panel components105 of the foldable display device 1000. The second substrate 112 can bemade of the same material as the first substrate 111, and can be made ofplastic such as polyimide, but is not limited thereto.

Referring to FIG. 3 , the mesh pattern 120 having a plurality ofopenings OA1 is formed on the first substrate 111. For example, the meshpattern 120 having a plurality of openings OA1 is disposed between thefirst substrate 111 and the second substrate 112.

The mesh pattern 120 of the foldable display device 1000 according to anexemplary embodiment of the present disclosure reduces the reflectivityat the pattern portion 165 formed in the folding area FA of the supportsubstrate 160, which is a structure disposed under the display panel 100and configured to support the display panel 100. Therefore, the meshpattern 120 can function to minimize the user's visual recognition ofthe pattern portion 165. Further, the mesh pattern 120 can easilydiffuse heat generated from the display panel 100 while the foldabledisplay device 1000 is driven. Therefore, the mesh pattern 120 canfunction to suppress the occurrence of mura in the folding area FA.

The mesh pattern 120 can be formed as an opaque metal layer having highreflectivity and low resistance by photo lithography. For example, themesh pattern 120 can be formed as a metal layer of copper (Cu),molybdenum (Mo) and aluminum (Al), but is not limited thereto.

Referring to FIG. 3 , the insulating layer 125 can be disposed on thefirst substrate 111 and the mesh pattern 120. The insulating layer 125can be formed to fully cover the mesh pattern 120. Specifically, thefoldable display panel 100 of the foldable display device 1000 accordingto an exemplary embodiment of the present disclosure can further includethe insulating layer 125 between the first substrate 111 and the secondsubstrate 112. The insulating layer 125 can be formed to fully cover themesh pattern 120. Thus, the mesh pattern 120 is not exposed to theoutside of the first substrate 111 or the second substrate 112.Therefore, it is possible to suppress a defect caused by corrosion whichcan occur when the mesh pattern 120 made of a metal material is exposedto the outside.

Referring to FIG. 3 , a buffer layer 113 is disposed on the secondsubstrate 112. The buffer layer 113 functions to enhance adhesionbetween the layers formed on the buffer layer 113 and the secondsubstrate 112 and block alkali elements discharged from under the bufferlayer 113. The buffer layer 113 can be formed as a single layer ofsilicon nitride (SiNx) or silicon oxide (SiOx), or a multi-layer ofsilicon nitride (SiNx) and silicon oxide (SiOx), but is not limitedthereto. However, the buffer layer 113 can be omitted depending on thetype and material of the second substrate 112 or the structure and typeof a transistor 140.

Referring to FIG. 3 , a plurality of barrier metal layers 130 isdisposed on the buffer layer 113. The plurality of barrier metal layers130 functions to protect active layers 141 of a plurality of thin filmtransistors 140. The plurality of barrier metal layers 130 can bedisposed to overlap the active layers 141 of the plurality of thin filmtransistors 140, respectively, on the buffer layer 113. In across-sectional view, each of the plurality of barrier metal layers 130can have a width equal to or greater than that of the active layer 141of each of the plurality of transistors 140. The plurality of barriermetal layers 130 can be made of various metal materials and can be in afloating state in which a voltage is not applied thereto. Alternatively,a constant voltage can be applied thereto.

Referring to FIG. 3 , an active buffer 114 is disposed on the pluralityof barrier metal layers 130 and the buffer layer 113. The active buffer114 is an insulating layer to insulate the plurality of barrier metallayers 130 from the active layers 141 of the transistors 140. The activebuffer 114 can be formed of the same material as the buffer layer 113.For example, the active buffer 114 can be formed as a single layer ofsilicon nitride (SiNx) or silicon oxide (SiOx), or a multi-layer ofsilicon nitride (SiNx) and silicon oxide (SiOx), but is not limitedthereto.

Referring to FIG. 3 , the thin film transistor 140 is disposed on theactive buffer 114. Specifically, the thin film transistor 140 can have atop gate coplanar structure, but is not necessarily limited thereto.

Specifically, the active layer 141 of the thin film transistor 140 isdisposed on the active buffer 114. The active layer 141 can be made oflow-temperature poly-silicon (LTPS) or oxide semiconductor, but is notlimited thereto. The active layer 141 includes a channel region 141 awhere a channel is formed, a source region 141 b connected to a sourceelectrode 142 and a drain region 141 c connected to a drain electrode143.

Referring to FIG. 3 , a gate insulating layer 115 is formed on theactive layer 141. The gate insulating layer 115 can be formed as asingle layer of silicon nitride (SiNx) or silicon oxide (SiOx), or amulti-layer of silicon nitride (SiNx) and silicon oxide (SiOx). In thegate insulating layer 115, contact holes for contact between the sourceelectrode 142 and the drain electrode 143, respectively, of thetransistor 140 and the source region 141 b and the drain region 141 c,respectively, of the active layer 141 of the transistor 140 are formed.

Referring to FIG. 3 , a gate electrode 144 of the thin film transistor140 is formed on the gate insulating layer 115. The gate electrode 144can be formed as a metal layer of molybdenum (Mo) or the like. Further,the gate electrode 144 is disposed on the gate insulating layer 115 soas to overlap the channel region 141 a of the active layer 141 of thethin film transistor 140.

Referring to FIG. 3 , an interlayer insulating layer 116 is disposed onthe gate electrode 144 and the gate insulating layer 115. The interlayerinsulating layer 116 can be made of an inorganic material such assilicon nitride (SiNx) or silicon oxide (SiOx) and formed as a singlelayer or a multi-layer, but is not limited thereto.

Referring to FIG. 3 , the source electrode 142 and the drain electrode143 of the thin film transistor 140 are formed on the interlayerinsulating layer 116. The source electrode 142 and the drain electrode143 are electrically connected to the active layer 141 through thecontact holes formed in the gate insulating layer 115 and the interlayerinsulating layer 116. The source electrode 142 and the drain electrode143 can be made of conductive materials, and the source electrode 142and the drain electrode 143 can be formed of the same material in thesame process. However, the present disclosure is not limited thereto.

Referring to FIG. 3 , a planarizing layer 117 is disposed on the sourceelectrode 142, the drain electrode 143 and the interlayer insulatinglayer 116. The planarizing layer 117 is configured to flatten an upperportion of the transistor 140. The planarizing layer 117 can be formedas a single layer as shown in FIG. 5 , but can also be formed as amulti-layer. The planarizing layer 117 can be made of an acryl-basedorganic material, but is not limited thereto. The planarizing layer 117can include a contact hole for electrical connection between the thinfilm transistor 140 and an anode 151.

Further, a passivation layer can be formed between the thin filmtransistor 140 and the planarizing layer 117. For example, thepassivation layer can be formed covering the thin film transistor 140 toprotect the thin film transistor 140 against permeation of moisture andoxygen. The passivation layer can be made of an inorganic material andformed as a single layer or a multi-layer, but is not limited thereto.

Referring to FIG. 3 , an organic light emitting diode 150 is disposed onthe planarizing layer 117. The organic light emitting diode 150 includesthe anode 151 electrically connected to the drain electrode 143 of thethin film transistor 140, an organic emission layer 152 disposed on theanode 151 and a cathode 153 formed on the organic emission layer 152. Ifthe foldable display device 1000 is a top emission type organic lightemitting display, the anode 151 can further include a reflective layerfor reflecting emitted light toward the cathode 153. Furthermore, theanode 151 can include a transparent conductive layer for supplying holesto the organic emission layer 152.

Referring to FIG. 3 , a bank 118 is disposed on the anode 151 and theplanarizing layer 117. The bank 118 is a structure to separate pixels Padjacent to each other in the display area DA and can define a pluralityof pixels P. The bank 118 can be made of an organic material, but is notlimited thereto.

Referring to FIG. 3 , an encapsulation layer 155 is disposed on thecathode 153. The encapsulation layer 155 minimizes degradation of thecomponents of the display panel 100 caused by moisture or oxygen. Theencapsulation layer 155 flattens an upper portion of the organic lightemitting diode 150. The encapsulation layer 155 can have a multilayerstructure in which an inorganic film and an organic film are laminated.For example, the encapsulation layer 155 can include at least oneorganic film and at least two inorganic films, and can have a multilayerstructure in which inorganic films and organic films are alternatelylaminated. The inorganic films have excellent barrier properties againstmoisture or oxygen, as compared with the organic films, due to thecharacteristics of the material. Therefore, preferably, the organicfilms are disposed between the inorganic films, but the presentdisclosure is not limited thereto. For example, the encapsulation layer155 can have a triple-layer structure including a first inorganic film156, an organic film 157 and a second inorganic film 158. For example,the first inorganic film 156 and the second inorganic film 158 are eachindependently made of one kind or more selected from silicon nitride(SiNx), silicon oxide (SiOx), silicon oxynitride (SiON) or aluminumoxide (Al₂O₃), but are not limited thereto. For example, the organicfilm 157 can be made of one kind or more selected from epoxy resin,polyimide, polyethylene and silicon oxycarbon (SiOC), but is not limitedthereto.

FIG. 4 is a diagram illustrating a structure of the support substrate160 of the foldable display device 1000 according to an exemplaryembodiment of the present disclosure.

The foldable display device 1000 according to an exemplary embodiment ofthe present disclosure includes the support substrate 160 disposed underthe display panel 100. The support substrate 160 can include a pluralityof opening patterns 165 formed corresponding to the folding area FA. Theopening patterns 165 facilitates folding of the support substrate 160 inthe folding area and returning back to original state, and thus canimprove the foldability of the foldable display device 1000.

Referring to FIG. 4 , each of the opening patterns 165 formed in thefolding area FA of the support substrate 160 can have an oval-like shapehaving a major axis along the Y-axis direction and a constant minor axislength. For example, each of the opening pattern 165 has a shape wheresemi-circles are respectively combined to both ends of a rectangularshape. Further, the opening patterns 165 can be spaced apart from eachother at a predetermined distance.

The support substrate 160 is configured to support the display panel 100and can be referred to as a bottom plate. The support substrate 160 canbe made of a metal material such as stainless steel (SUS), SUScontaining other metals, such as nickel (Ni), iron (Fe), aluminum(Al)-based or magnesium (Mg). The SUS has high restoring force andstrength, and, thus, even if the support substrate 160 decreases inthickness, the support structure 180 can maintain a desired strength.Thus, the support structure 180 supports the display panel 100 and alsoallows a decrease in the thickness of the foldable display device 1000.Therefore, it is possible to reduce the radius of curvature of thefolding area FA. However, the support substrate 160 is not limitedthereto. The support substrate 160 can also be made of a polymer such aspolymethylmetacrylate (PMMA), polycarbonate (PC), polyvinyl alcohol(PVA), acrylonitrile butadiene-styrene (ABS), polyethylene terephthalate(PET), silicone or polyurethane (PU).

The support substrate 160 can have a thickness of from 20 μm to 1000 μm,or from 100 μm to 200 μm. If the thickness of the support substrate 160satisfies the above ranges, the support substrate 160 can be foldedwhile maintaining the strength and the supporting function.

The opening patterns 165 of the support substrate 160 can be formed invarious shapes or at various distances in the folding area FA. Forexample, each of the opening patterns 165 can be formed in a rectangularshape, a diamond shape or a circular shape.

FIG. 5 illustrates a structure of a unit pixel and a mesh pattern of thefoldable display device 1000 according to an exemplary embodiment of thepresent disclosure.

Here, (a) of FIG. 5 is an enlarged view of an area A of the folding areaFA shown in FIG. 1 , (b) of FIG. 5 is an enlarged view of an area B ofthe second folding boundary area BA2 in the folding boundary areas BA1and BA2 shown in FIG. 1 , and (c) of FIG. 5 is an enlarged view of anarea C of the second non-folding area NFA2 in the non-folding areas NFA1and NFA2 shown in FIG. 1 .

Referring to (a)-(c) of FIG. 5 , the display panel 100 of the foldabledisplay device 1000 according to an exemplary embodiment of the presentdisclosure includes a plurality of sub-pixels SP1, SP2, SP3, SP4, SP5,SP6, SP7 and SP8. The plurality of sub-pixels SP1, SP2, SP3, SP4, SP5,SP6, SP7 and SP8 is disposed in a matrix form.

Referring to (a)-(c) of FIG. 5 , some sub-pixels SP1, SP2, SP3 and SP4from among the plurality of sub-pixels SP1, SP2, SP3, SP4, SP5, SP6, SP7and SP8 can form a first pixel P1. The other sub-pixels SP5, SP6, SP7and SP8 can form a second pixel P2.

Further, the first pixel P1 and the second pixel P2 form a unit.Therefore, unit pixels UP can be disposed repeatedly inside the displayarea DA of the display panel 100.

Referring to (a)-(c) of FIG. 5 , the first pixel P1 can include a firstsub-pixel SP1, a second sub-pixel SP2, a third sub-pixel SP3 and afourth sub-pixel SP4.

Each of the first sub-pixel SP1 and the second sub-pixel SP2 isalternately disposed in a first direction (X-axis direction). The thirdsub-pixel SP3 and the fourth sub-pixel SP4 are disposed adjacent to thefirst sub-pixel SP1 and the second sub-pixel SP2, respectively, in asecond direction (Y-axis direction). Each of the third sub-pixel SP3 andthe fourth sub-pixel SP4 is alternately disposed in the first direction.However, the present disclosure is not limited thereto. The layout ofthe sub-pixels SP1, SP2, SP3 and SP4 can be changed in various waysdepending the resolution or the like.

The first sub-pixel SP1, the second sub-pixel SP2, the third sub-pixelSP3 and the fourth sub-pixel SP4 can display different colors from eachother, or can display the same color depending on the design. Theplurality of sub-pixels SP1, SP2, SP3 and SP4 can each independentlydisplay any one color of red, green, blue and white. For example, thefirst sub-pixel SP1 can display red, the second sub-pixel SP2 candisplay blue, and the third sub-pixel SP3 and the fourth sub-pixel SP4can display green, but are not limited thereto.

Further, referring to (a)-(c) of FIG. 5 , the second sub-pixel SP2 isdisposed adjacent to the first pixel P1 in the second direction (Y-axisdirection). The second pixel P2 can include a fifth sub-pixel SP5, asixth sub-pixel SP6, a seventh sub-pixel SP7, and an eighth sub-pixelSP8.

Each of the fifth sub-pixel SP5 and the sixth sub-pixel SP6 isalternately disposed in the first direction (X-axis direction). Theseventh sub-pixel SP7 and the eighth sub-pixel SP8 are disposed adjacentto the fifth sub-pixel SP5 and the sixth sub-pixel SP6, respectively, inthe second direction (Y-axis direction). Each of the seventh sub-pixelSP7 and the eighth sub-pixel SP8 is alternately disposed in the firstdirection. However, the present disclosure is not limited thereto. Thelayout of the sub-pixels SP5, SP6, SP7 and SP8 can be changed in variousways depending the resolution or the like.

The fifth sub-pixel SP5, the sixth sub-pixel SP6, the seventh sub-pixelSP7 and the eighth sub-pixel SP8 can display different colors from eachother, or can display the same color depending on the design. Theplurality of sub-pixels SP5, SP6, SP7 and SP8 can each independentlydisplay any one color of red, green, blue and white. For example, thefifth sub-pixel SP5 can display blue, the sixth sub-pixel SP6 candisplay red, and the seventh sub-pixel SP7 and the eighth sub-pixel SP8can display green, but are not limited thereto.

Referring to (a)-(c) of FIG. 5 , the plurality of sub-pixels SP1, SP2,SP3, SP4, SP5, SP6, SP7 and SP8 respectively includes emission areasEA1, EA2, EA3, EA4, EA5, EA6, EA7 and EA8 where light is emitted andnon-emission areas NEA1, NEA2, NEA3, NEA4, NEA5, NEA6, NEA7 and NEA8where light is not substantially emitted due to the bank 118. In thepresent disclosure, exposed areas of the anodes 151 without beingcovered by the bank 118 are defined as the emission areas EA1, EA2, EA3,EA4, EA5, EA6, EA7 and EA8. Further, the other areas are defined as thenon-emission areas NEA1, NEA2, NEA3, NEA4, NEA5, NEA6, NEA7 and NEA8.

Referring to (a)-(c) of FIG. 5 , the emission areas EA1, EA2, EA3, EA4,EA5, EA6, EA7 and EA8 of the plurality of sub-pixels SP1, SP2, SP3, SP4,SP5, SP6, SP7 and SP8 are illustrated as having an octagonal shape.However, this is just an example, the shape of the emission areas EA1,EA2, EA3, EA4, EA5, EA6, EA7 and EA8 is not limited to the octagonalshape. For example, the emission areas EA1, EA2, EA3, EA4, EA5, EA6, EA7and EA8 of the plurality of sub-pixels SP1, SP2, SP3, SP4, SP5, SP6, SP7and SP8 can also have any polygonal shape except a circular shape, anoval shape and an octagonal shape.

Here, (a) of FIG. 5 is an enlarged view of the area A of the foldingarea FA shown in FIG. 1 . Referring to (a) of FIG. 5 , the foldabledisplay device 1000 according to an exemplary embodiment of the presentdisclosure can include the plurality of first mesh patterns 120 a havingthe first openings OA1 in the folding area FA. The first opening OA1formed in each of the plurality of first mesh patterns 120 a in thefolding area FA can have a length L1 in the second direction (Y-axisdirection). Further, each of the plurality of first mesh patterns 120 ain the folding area FA can have a line width W1 in the first direction(X-axis direction).

Further, (b) of FIG. 5 is an enlarged view of the area B of the secondfolding boundary area BA2 in the folding boundary areas BA1 and BA2shown in FIG. 1 . Referring to (b) of FIG. 5 , the foldable displaydevice 1000 according to an exemplary embodiment of the presentdisclosure can include the plurality of second mesh patterns 120 bhaving the second openings OA2 in the second folding boundary area BA2.The second opening OA2 formed in each of the plurality of second meshpatterns 120 b in the second folding boundary area BA2 can have a lengthL2 in the second direction (Y-axis direction). Further, each of theplurality of second mesh patterns 120 b in the second folding boundaryarea BA2 can have the line width W1 in the first direction (X-axisdirection).

Also, (c) of FIG. 5 is an enlarged view of the area C of the secondnon-folding area NFA2 in the non-folding areas NFA1 and NFA2 shown inFIG. 1 . Referring to (c) of FIG. 5 , the foldable display device 1000according to an exemplary embodiment of the present disclosure caninclude the plurality of third mesh patterns 120 c having the thirdopenings OA3 in the second non-folding area NFA2 in the non-foldingareas NFA1 and NFA2. The third opening OA3 formed in each of theplurality of third mesh patterns 120 c in the second non-folding areaNFA2 can have a length L3 in the second direction (Y-axis direction).Further, each of the plurality of third mesh patterns 120 c in thesecond non-folding area NFA2 can have the line width W1 in the firstdirection (X-axis direction).

Here, in the foldable display device 1000 according to an exemplaryembodiment of the present disclosure, all the first mesh patterns 120 a,the second mesh patterns 120 b and the third mesh pattern 120 c can havethe same line width W1 in the first direction (X-axis direction).

Referring to (a)-(c) of FIG. 5 , in the foldable display device 1000according to an exemplary embodiment of the present disclosure, theopenings OA1 of the mesh patterns 120 a in the folding area FA can beformed smaller in size than the openings OA3 of the mesh patterns 120 cin the non-folding areas NFA1 and NFA2.

More specifically, the length L1, which is the length of the opening OA1of the mesh pattern 120 a in the folding area FA in the seconddirection, can be smaller than the length L3, which is the length of theopening OA3 of the mesh pattern 120 c in the second non-folding areaNFA2 in the second direction.

Further, referring to (a)-(c) of FIG. 5 , in the foldable display device1000 according to an exemplary embodiment of the present disclosure, theopening OA1 of the mesh pattern 120 a in the folding area FA can beformed smaller in size than the opening OA2 of the mesh pattern 120 b inthe folding boundary areas BA1 and BA2.

More specifically, the length L1, which is the length of the opening OA1of the mesh pattern 120 a in the folding area FA in the seconddirection, can be smaller than the length L2, which is the length of theopening OA2 of the mesh pattern 120 b in the second folding boundaryarea BA2 in the second direction.

Further, referring to (a)-(c) of FIG. 5 , in the foldable display device1000 according to an exemplary embodiment of the present disclosure, theopening OA2 of the mesh pattern 120 b in the folding boundary areas BA1and BA2 can be formed smaller in size than the opening OA3 of the meshpattern 120 c in the non-folding areas NFA1 and NFA2.

More specifically, the length L2, which is the length of the opening OA2of the mesh pattern 120 b in the second folding boundary area BA2 in thesecond direction, can be smaller than the length L3, which is the lengthof the opening OA3 of the mesh pattern 120 c in the second non-foldingarea NFA2 in the second direction.

For example, in the foldable display device 1000 according to anexemplary embodiment of the present disclosure, the opening OA2 of themesh pattern 120 b in the folding boundary areas BA1 and BA2 can begreater in size than the opening OA1 of the mesh pattern 120 a in thefolding area FA. Further, the opening OA2 of the mesh pattern 120 b inthe folding boundary areas BA1 and BA2 can be smaller in size than theopening OA3 of the mesh pattern 120 c in the non-folding areas NFA1 andNFA2.

In the foldable display device 1000 according to an exemplary embodimentof the present disclosure, the opening OA1 of the mesh pattern 120 a inthe folding area FA can be formed smaller in size than the opening OA3of the mesh pattern 120 c in the non-folding areas NFA1 and NFA2.Further, the opening OA3 of the mesh pattern 120 c in the non-foldingareas NFA1 and NFA2 can be formed greater in size than the opening OA1of the mesh pattern 120 a in the folding area FA. Furthermore, theopening OA2 of the mesh pattern 120 b in the folding boundary areas BA1and BA2 can be formed greater in size than the opening OA1 of the meshpattern 120 a in the folding area FA. Further, the opening OA2 of themesh pattern 120 b in the folding boundary areas BA1 and BA2 can beformed smaller in size than the opening OA3 of the mesh pattern 120 c inthe non-folding areas NFA1 and NFA2.

For example, in the foldable display device 1000 according to anexemplary embodiment of the present disclosure, the openings OA1, OA2and OA3 of the mesh patterns 120 a, 120 b and 120 c increase in sizefrom the folding area FA toward the non-folding areas NFA1 and NFA2.Thus, the mesh patterns 120 a, 120 b and 120 c reduce the reflectivityat the pattern portion 165 formed in the folding area FA of the supportsubstrate 160, which is a structure disposed under the display panel 100and configured to support the display panel 100. Therefore, the meshpatterns 120 a, 120 b and 120 c can function to minimize the user'svisual recognition of the pattern portion 165. Further, the meshpatterns 120 a, 120 b and 120 c can easily diffuse heat generated fromthe display panel 100 while the foldable display device 1000 is driven.Therefore, the mesh patterns 120 a, 120 b and 120 c can function tosuppress the occurrence of mura in the folding area FA.

Further, in the foldable display device 1000 according to an exemplaryembodiment of the present disclosure, all the openings OA1 of the meshpatterns 120 a in the folding area FA can have the same size.

Further, in the foldable display device 1000 according to an exemplaryembodiment of the present disclosure, all the openings OA3 of theplurality of mesh patterns 120 c in the non-folding areas NFA1 and NFA2can have the same size.

Furthermore, in the foldable display device 1000 according to anexemplary embodiment of the present disclosure, all the openings OA2 ofthe plurality of mesh patterns 120 b in the folding boundary areas BA1and BA2 can have the same size.

Further, referring to (a)-(c) of FIG. 5 , in the foldable display device1000 according to an exemplary embodiment of the present disclosure,each pattern of the mesh pattern 120 can be formed corresponding in sizeto each of a plurality of unit pixels in the display area DA.

Specifically, one of the first mesh patterns 120 a having the firstopenings OA1 in the folding area FA, the second mesh patterns 120 bhaving the second openings OA2 in the first folding boundary area BA1and the second folding boundary area BA2 and the third mesh patterns 120c having the third openings OA3 in the first non-folding area NFA1 andthe second non-folding area NFA2 is formed corresponding in size to eachof a plurality of unit pixels. Thus, all the patterns of the meshpattern 120 can have the same size.

Further, referring to (a)-(c) of FIG. 5 , in the foldable display device1000 according to an exemplary embodiment of the present disclosure, theopening OA of the mesh pattern 120 can be disposed corresponding to atleast two of the plurality of sub-pixels.

Further, in the folding area FA, the folding boundary areas BA1 and BA2and the non-folding areas NFA1 and NFA2, the openings OA1, OA2 and OA3of the plurality of mesh patterns 120 a, 120 b and 120 c can be formedat the same position in the respective unit pixels.

More specifically, the first openings OA1 of the plurality of first meshpatterns 120 a in the folding area FA can be formed at the same positionin the respective unit pixels. Further, the second openings OA2 of theplurality of second mesh patterns 120 b in the folding boundary areasBA1 and BA2 can be formed at the same position in the respective unitpixels. Further, the third openings OA3 of the plurality of third meshpatterns 120 c in the non-folding areas NFA1 and NFA2 can be formed atthe same position in the respective unit pixels.

For example, the foldable display device 1000 according to an exemplaryembodiment of the present disclosure includes the mesh pattern 120having the plurality of openings OA and made of a metal material betweenthe flexible substrates 111 and 112. Further, the openings OA of themesh pattern 120 increase in size from the folding area FA toward thenon-folding areas NFA. Thus, the mesh pattern 120 reduces thereflectivity at the pattern portion 165 of the support substrate 160,which is a structure configured to support the display panel 100.Therefore, the mesh pattern 120 can minimize the user's visualrecognition of the pattern portion 165.

Further, the mesh pattern 120 can easily diffuse heat generated from thedisplay panel 100 while the foldable display device 1000 according to anexemplary embodiment of the present disclosure is driven. Therefore, themesh pattern 120 can suppress the occurrence of mura in the folding areaFA.

FIG. 6 illustrates a structure of a unit pixel and a mesh pattern of afoldable display device 1100 according to another exemplary embodimentof the present disclosure.

The foldable display device 1100 shown in (a)-(c) of FIG. 6 issubstantially the same as the foldable display device 1000 shown in(a)-(c) of FIG. 5 except that a line width W of the wiring line of themesh pattern 120 gradually increases from the folding area FA toward thenon-folding areas NFA. Thus, repeated description will be omitted or abrief description of the same elements may be provided.

Referring to (a) of FIG. 6 , the foldable display device 1100 accordingto another exemplary embodiment of the present disclosure can includethe plurality of first mesh patterns 120 a having the first openings OA1in the folding area FA.

Further, the first opening OA1 formed in each of the plurality of firstmesh patterns 120 a in the folding area FA can have the length L1 in thesecond direction (Y-axis direction). Further, referring to (a) of FIG. 6, each of the plurality of first mesh patterns 120 a in the folding areaFA can have the line width W1 in the first direction (X-axis direction).

Referring to (b) of FIG. 6 , the foldable display device 1100 accordingto another exemplary embodiment of the present disclosure can includethe plurality of second mesh patterns 120 b having the second openingsOA2 in the second folding boundary area BA2.

Further, the second opening OA2 formed in each of the plurality ofsecond mesh patterns 120 b in the second folding boundary area BA2 canhave the length L2 in the second direction (Y-axis direction). Further,referring to (b) of FIG. 6 , each of the plurality of second meshpatterns 120 b in the second folding boundary area BA2 can have a linewidth W2 in the first direction (X-axis direction).

Referring to (c) of FIG. 6 , the foldable display device 1100 accordingto another exemplary embodiment of the present disclosure can includethe plurality of third mesh patterns 120 c having the third openings OA3in the second non-folding area NFA2 in the non-folding areas NFA1 andNFA2.

Further, the third openings OA3 formed in each of the plurality of thirdmesh patterns 120 c in the second non-folding area NFA2 can have thelength L3 in the second direction (Y-axis direction). Further, referringto FIG. 6(c), each of the plurality of third mesh patterns 120 c in thesecond non-folding area NFA2 can have a line width W3 in the firstdirection (X-axis direction).

In the foldable display device 1100 according to another exemplaryembodiment of the present disclosure, the line width W1 of the firstmesh pattern 120 a can be greater than the line width W2 of the secondmesh pattern 120 b. Further, the line width W2 of the second meshpattern 120 b can be greater than the line width W3 of the third meshpattern 120 c.

For example, in the foldable display device 1100 according to anotherexemplary embodiment of the present disclosure, the line width W2 of thewiring line of the second mesh pattern 120 b in the folding boundaryarea BA between the folding area FA and the non-folding area NFA can besmaller than the line width W1 of the wiring line of the first meshpattern 120 a in the folding area FA. Further, the line width W2 of thewiring line of the second mesh pattern 120 b in the folding boundaryarea BA can be greater than the line width W3 of the wiring line of themesh pattern 120 c in the non-folding areas NFA1 and NFA2.

For example, referring to (a)-(c) of FIG. 6 , in the foldable displaydevice 1100 according to another exemplary embodiment of the presentdisclosure, as the lengths L1, L2 and L3 of the mesh patterns 120 a, 120b and 120 c in the second direction (Y-axis direction), i.e., the sizesof the openings OA1, OA2 and OA3 of the mesh patterns 120 a, 120 b and120 c, increase, the line widths W1, W2 and W3 of the mesh patterns 120a, 120 b and 120 c can decrease.

FIG. 7 is a plan view of a foldable display device 2000 according to yetanother exemplary embodiment of the present disclosure.

FIG. 8A through FIG. 8C illustrate a structure of a unit pixel and amesh pattern 220 of the foldable display device 2000 according to yetanother exemplary embodiment of the present disclosure.

FIG. 8A is an enlarged view of an area D of the folding area FA shown inFIG. 7 . FIG. 8B is an enlarged view of an area E of the second foldingboundary area BA2 shown in FIG. 7 . FIG. 8C is an enlarged view of anarea F of the second non-folding area NFA2 shown in FIG. 7 .

The foldable display device 2000 according to yet another exemplaryembodiment of the present disclosure shown in FIG. 7 and FIG. 8A throughFIG. 8C is substantially the same as the foldable display device 1000shown in FIG. 3 except that openings OA21, OA22 and OA23 of a meshpattern 220 in the folding boundary areas BA1 and BA2 gradually increasein size from the folding area FA toward the non-folding areas NFA, i.e.,as getting farther away from the folding area FA. Thus, repeateddescription will be omitted or a brief description of the same elementsmay be provided.

Referring to FIG. 7 , the foldable display device 2000 according to yetanother exemplary embodiment of the present disclosure can include amesh pattern 220 having a plurality of openings OA between a firstsubstrate 211 on which components of a foldable display panel 200 areformed and a second substrate 212.

Referring to FIG. 8A, the foldable display device 2000 according to yetanother exemplary embodiment of the present disclosure can include aplurality of first mesh patterns 220 a having first openings OA11 in thefolding area FA.

Referring to FIG. 8B, the foldable display device 2000 according to yetanother exemplary embodiment of the present disclosure can include aplurality of second mesh patterns 220 b having second openings OA21, aplurality of third mesh patterns 220 c having third openings OA22 and aplurality of fourth mesh patterns 220 d having fourth openings OA23 inthe second folding boundary area BA2, which are the folding boundaryareas BA1 and BA2. The mesh pattern 220 formed in the first foldingboundary area BA1 can have the openings OA identical in size to theopenings OA in the second folding boundary area BA2.

Further, referring to FIG. 8C, the foldable display device 2000according to yet another exemplary embodiment of the present disclosurecan include a plurality of fifth mesh patterns 220 e having fifthopenings OA31 in the second non-folding area NFA2. The mesh pattern 220formed in the first non-folding area NFA1 can have the openings OAidentical in size to the openings OA in the second non-folding areaNFA2.

In the foldable display device 2000 according to yet another exemplaryembodiment of the present disclosure, the first openings OA11 of thefirst mesh patterns 220 a in the folding area FA can be formed smallerin size than the fifth openings OA31 of the fifth mesh patterns 220 e inthe non-folding areas NFA1 and NFA2.

Further, in the foldable display device 2000 according to yet anotherexemplary embodiment of the present disclosure, the first openings OA11of the first mesh patterns 220 a in the folding area FA can be formedsmaller in size than the second openings OA21 of the second meshpatterns 220 b, the third openings OA22 of the third mesh patterns 220 cand the fourth openings OA23 of the fourth mesh patterns 220 d in thefolding boundary areas BA1 and BA2.

Further, in the foldable display device 2000 according to yet anotherexemplary embodiment of the present disclosure, the second openings OA21of the second mesh patterns 220 b, the third openings OA22 of the thirdmesh patterns 220 c and the fourth openings OA23 of the fourth meshpatterns 220 d in the folding boundary areas BA1 and BA2 can be formedsmaller than the fifth openings OA31 of the fifth mesh patterns 220 e inthe non-folding areas NFA1 and NFA2.

For example, in the foldable display device 2000 according to yetanother exemplary embodiment of the present disclosure, the secondopenings OA21 of the second mesh patterns 220 b, the third openings OA22of the third mesh patterns 220 c and the fourth openings OA23 of thefourth mesh patterns 220 d in the folding boundary areas BA1 and BA2 canbe greater in size than the first openings OA11 of the first meshpatterns 220 a in the folding area FA. Further, the second openings OA21of the second mesh patterns 220 b, the third openings OA22 of the thirdmesh patterns 220 c and the fourth openings OA23 of the fourth meshpatterns 220 d in the folding boundary areas BA1 and BA2 can be smallerthan the fifth openings OA31 of the fifth mesh patterns 220 e in thenon-folding areas NFA1 and NFA2.

Here, all the openings OA11 of the plurality of first mesh patterns 220a in the folding area FA can have the same size.

Further, all the openings OA31 of the plurality of fifth mesh patterns220 e in the non-folding areas NFA1 and NFA2 can have the same size.

Referring to FIG. 8B, in the foldable display device 2000 according toyet another exemplary embodiment of the present disclosure, the secondopenings OA21 of the second mesh patterns 220 b, the third openings OA22of the third mesh patterns 220 c and the fourth openings OA23 of thefourth mesh patterns 220 d in the folding boundary areas BA1 and BA2 cangradually increase in size as getting farther away from the folding areaFA.

Specifically, referring to FIG. 8B, in the area E of FIG. 7 included inthe second folding boundary area BA2, the second opening OA21 of thesecond mesh pattern 220 b of a unit pixel UP21 most adjacent to thefolding area FA can have a length L21. Further, the third opening OA22of the third mesh pattern 220 c of a unit pixel UP22 farther from thefolding area FA than the unit pixel UP21 can have a length L22. Further,the fourth opening OA23 of the fourth mesh pattern 220 d of a unit pixelUP23 farther from the folding area FA than the unit pixel UP22 can havea length L23.

For example, referring to FIG. 8B, in the second folding boundary areaBA2, the length L21 of the second opening OA21 of the unit pixel U21 canbe smaller than the length L22 of the third opening OA22 of the unitpixel UP22. Further, in the second folding boundary area BA2, the lengthL22 of the third opening OA22 of the unit pixel UP22 can be smaller thanthe length 23 of the fourth opening OA23 of the unit pixel UP23.

For example, in the second folding boundary area BA2, the second openingOA21 of the second mesh pattern 220 b can be formed smaller than thethird opening OA22 of the third mesh pattern 220 c. Further, in thesecond folding boundary area BA2, the third opening OA22 of the thirdmesh pattern 220 c can be formed smaller than the fourth opening OA23 ofthe fourth mesh pattern 220 d.

In the foldable display device 2000 according to yet another exemplaryembodiment of the present disclosure, the second openings OA21 of thesecond mesh patterns 220 b, the third openings OA22 of the third meshpatterns 220 c and the fourth openings OA23 of the fourth mesh patterns220 d in the folding boundary areas BA1 and BA2 gradually increase insize as getting farther away from the folding area FA. Thus, thereflectivity in the folding boundary areas BA1 and BA2 can be reduced.Therefore, it is possible to minimize the user's visual recognition of apattern portion in the folding boundary areas BA1 and BA2.

FIG. 9 is a plan view of a foldable display device 3000 according tostill another exemplary embodiment of the present disclosure.

FIG. 10A through FIG. 10C illustrate a detailed structure of a unitpixel and a mesh pattern 320 of the foldable display device 3000according to still another exemplary embodiment of the presentdisclosure.

FIG. 10A is an enlarged view of an area G of the folding area FA shownin FIG. 9 . FIG. 10B is an enlarged view of an area H of the secondfolding boundary area BA2 shown in FIG. 9 . FIG. 10C is an enlarged viewof an area I of the second non-folding area NFA2 shown in FIG. 9 .

The foldable display device 3000 according to still another exemplaryembodiment of the present disclosure shown in FIG. 9 and FIG. 10Athrough FIG. 10C is substantially the same as the foldable displaydevice 1000 shown in FIG. 3 except that openings OA11, OA12, OA21, OA22,OA31 and OA32 of a mesh pattern 320 in the folding area FA, the foldingboundary areas BA1 and BA2 and the non-folding area NFA graduallyincrease in size from a central portion of the folding area FA towardthe non-folding areas NFA, i.e., from the folding area FA toward thenon-folding areas NFA. Thus, repeated description will be omitted or abrief description of the same elements may be provided.

Referring to FIG. 10A, in the foldable display device 3000 according tostill another exemplary embodiment of the present disclosure, thefolding area FA can include a first mesh pattern 320 a having the firstopening OA11 corresponding to a first unit pixel UP11. Further, thefolding area FA can include a second mesh pattern 320 b having thesecond opening OA12 corresponding to a second unit pixel UP12.

The first opening OA11 of the first mesh pattern 320 a can have a lengthL11 in the second direction (Y-axis direction). Further, the first meshpattern 320 a can have a line width W11 in the first direction (X-axisdirection).

The second opening OA12 of the second mesh pattern 320 b can have alength L12 in the second direction (Y-axis direction). Further, thesecond mesh pattern 320 b can have a line width W12 in the firstdirection (X-axis direction).

Referring to FIG. 10B, in the foldable display device 3000 according tostill another exemplary embodiment of the present disclosure, the secondfolding boundary area BA2 can include a third mesh pattern 320 c havingthe third opening OA21 corresponding to a third unit pixel UP21.Further, the second folding boundary area BA2 can include a fourth meshpattern 320 d having the fourth opening OA22 corresponding to a fourthunit pixel UP22.

The third opening OA21 of the third mesh pattern 320 c can have a lengthL21 in the second direction (Y-axis direction). Further, the third meshpattern 320 c can have a line width W21 in the first direction (X-axisdirection).

The fourth opening OA22 of the fourth mesh pattern 320 d can have alength L22 in the second direction (Y-axis direction). Further, thefourth mesh pattern 320 d can have a line width W22 in the firstdirection (X-axis direction).

Referring to FIG. 10C, in the foldable display device 3000 according tostill another exemplary embodiment of the present disclosure, the secondnon-folding area NFA2 can include a fifth mesh pattern 320 e having thefifth opening OA31 corresponding to a fifth unit pixel UP31. Further,the second non-folding area NFA2 can include a sixth mesh pattern 320 fhaving the sixth opening OA32 corresponding to a sixth unit pixel UP32.

The fifth opening OA31 of the fifth mesh pattern 320 e can have a lengthL31 in the second direction (Y-axis direction). Further, the fifth meshpattern 320 e can have a line width W31 in the first direction (X-axisdirection).

The sixth opening OA32 of the sixth mesh pattern 320 f can have a lengthL32 in the second direction (Y-axis direction). Further, the sixth meshpattern 320 f can have a line width W32 in the first direction (X-axisdirection).

Referring to FIG. 10A through FIG. 10C, the length L11 of the firstopening OA11 of the first mesh pattern 320 a and the length L12 of thesecond opening OA12 of the second mesh pattern 320 b in the folding areaFA can be smaller than the length L21 of the third opening OA21 of thethird mesh pattern 320 c and the length L22 of the fourth opening OA22of the fourth mesh pattern 320 d in the second folding boundary areaBA2.

Further, the length L21 of the third opening OA21 of the third meshpattern 320 c and the length L22 of the fourth opening OA22 of thefourth mesh pattern 320 d in the second folding boundary area BA2 can besmaller than the length L31 of the fifth opening OA31 of the fifth meshpattern 320 e and the length L32 of the sixth opening OA32 of the sixthmesh pattern 320 f in the second non-folding area NFA2.

Further, referring to FIG. 10A, in the folding area FA, the length L11of the first opening OA11 of the first mesh pattern 320 a can be smallerthan the length L12 of the second opening OA12 of the second meshpattern 320 b. Further, the line width W11 of the first mesh pattern 320a can be greater than the line width W12 of the second mesh pattern 320b. For example, the openings OA of the mesh pattern 320 in the foldingarea FA can gradually increase in size from a central portion of thefolding area FA toward the non-folding areas NFA. Further, a line widthW of the mesh pattern 320 can gradually decrease from the centralportion of the folding area FA toward the non-folding areas NFA.

Referring to FIG. 10B, in the second folding boundary area BA2, thelength L21 of the third opening OA21 of the third mesh pattern 320 c canbe smaller than the length L22 of the fourth opening OA22 of the fourthmesh pattern 320 d. Further, the line width W21 of the third meshpattern 320 c can be greater than the line width W22 of the fourth meshpattern 320 d. For example, the openings OA of the mesh pattern 320 inthe second folding boundary area BA2 can gradually increase in size fromthe folding area FA toward the non-folding areas NFA. Further, the linewidth W of the mesh pattern 320 can gradually decrease from the foldingarea FA toward the non-folding areas NFA.

Referring to FIG. 10C, in the second non-folding area NFA2, the lengthL31 of the fifth opening OA31 of the fifth mesh pattern 320 e can besmaller than the length L32 of the sixth opening OA32 of the sixth meshpattern 320 f. Further, the line width W31 of the fifth mesh pattern 320e can be greater than the line width W32 of the sixth mesh pattern 320f. For example, the openings OA of the mesh pattern 320 in the secondnon-folding area NFA2 can gradually increase in size from the foldingarea FA toward the non-folding areas NFA. Further, the line width W ofthe mesh pattern 320 can gradually decrease from the folding area FAtoward the non-folding areas NFA.

In the foldable display device 3000 according to still another exemplaryembodiment of the present disclosure, the openings OA11, OA12, OA21,OA22, OA31 and OA32 of the mesh pattern 320 in the folding area FA, thefolding boundary areas BA1 and BA2 and the non-folding area NFAgradually increase in size from the central portion of the folding areaFA toward the non-folding areas NFA, i.e., from the folding area FAtoward the non-folding areas NFA. Further, the line width W of the meshpattern 320 gradually decreases from the folding area FA toward thenon-folding areas NFA. Thus, the reflectivity at the pattern portion ofthe support substrate 160 can be reduced. Therefore, it is possible tominimize the user's visual recognition of the pattern portion 165.Further, heat generated from the display panel 100 during driving can beeasily diffused. Therefore, it is possible to suppress the occurrence ofmura in the folding area FA.

FIG. 11 is a plan view of a foldable display device 4000 according tostill another exemplary embodiment of the present disclosure.

The foldable display device 4000 according to still another exemplaryembodiment of the present disclosure shown in FIG. 11 through FIG. 13 issubstantially the same as the foldable display device 1000 shown in FIG.3 except that the folding area FA includes a first folding area FA1 anda second folding area FA2 spaced apart from the first folding area FA1.Thus, repeated description will be omitted.

Referring to FIG. 11 , the foldable display device 4000 according tostill another exemplary embodiment of the present disclosure includes atleast one folding area FA1 and FA2 and two or more non-folding areasNFA1, NFA2 and NFA3. The folding areas FA1 and FA2 refer to folded areaswhen the foldable display device 4000 is folded. The foldable displaydevice 4000 can be folded with a specific radius of curvature around afolding axis. The non-folding areas NFA1, NFA2 and NFA3 refer tonon-folded areas when the foldable display device 4000 is folded. Forexample, the non-folding areas NFA1, NFA2 and NFA3 maintain a flat statewhen the foldable display device 4000 is folded. The non-folding areasNFA1, NFA2 and NFA3 can be located on one side or both sides of thefolding areas FA1 and FA2. For example, if folding axes of the foldingareas FA1 and FA2 are formed in the Y-axis direction, the non-foldingareas NFA1, NFA2 and NFA3 are defined as extending from the foldingareas FA1 and FA2 in the X-axis direction perpendicular to the foldingaxes.

The foldable display device 4000 according to still another exemplaryembodiment of the present disclosure includes a first folding area FA1,a second folding area FA2, the first non-folding area NFA1, the secondnon-folding area NFA2 and a third non-folding area NFA3. The firstfolding area FA1 can be disposed between the first non-folding area NFA1and the second non-folding area NFA2. Further, the second folding areaFA2 can be disposed between the second non-folding area NFA2 and thethird non-folding area NFA3.

Further, a first folding boundary area BA11 can be disposed between thefirst non-folding area NFA1 and the first folding area FA1. Further, asecond folding boundary area BA12 can be disposed between the firstfolding area FA1 and the second non-folding area NFA2. Furthermore, athird folding boundary area BA21 can be disposed between the secondnon-folding area NFA2 and the second folding area FA2. Moreover, afourth folding boundary area BA22 can be disposed between the secondfolding area FA2 and the third non-folding area NFA3.

In the foldable display device 4000 according to still another exemplaryembodiment of the present disclosure, the folding area FA includes thefirst folding area FA1 and the second folding area FA2 spaced apart fromthe first folding area FA1. The first folding area FA1 can be anin-folding area and the second folding area FA2 can be an out-foldingarea.

In the foldable display device 4000 according to still another exemplaryembodiment of the present disclosure, openings OA of a mesh pattern 420in the first folding area FA1 and the second folding area FA2 can beformed smaller in size than openings OA3 of the mesh pattern 420 in thenon-folding areas NFA1, NFA2 and NFA3.

Further, in the foldable display device 4000 according to still anotherexemplary embodiment of the present disclosure, the openings OA of themesh pattern 420 in the first folding area FA1 and the second foldingarea FA2 can be formed smaller in size than the openings OA of the meshpattern 420 in the folding boundary areas BA11, BA12, BA21 and BA22.

Further, in the foldable display device 4000 according to still anotherexemplary embodiment of the present disclosure, the openings OA of themesh pattern 420 in the folding boundary areas BA11, BA12, BA21 and BA22can be formed smaller in size than openings OA3 of the mesh pattern 420in the non-folding areas NFA1, NFA2 and NFA3.

Here, in the foldable display device 4000 according to still anotherexemplary embodiment of the present disclosure, the openings OA of themesh pattern 420 in the first folding area FA1 can be identical in sizeto the openings OA of the mesh pattern 420 in the second folding areaFA2.

For example, in the foldable display device 4000 according to stillanother exemplary embodiment of the present disclosure, the openings OAof the mesh pattern 420 in the folding boundary areas BA11, BA12, BA21and BA22 can be greater in size than the openings OA of the mesh pattern420 in the folding areas FA1 and FA2. Further, the openings OA of themesh pattern 420 in the folding boundary areas BA11, BA12, BA21 and BA22can be smaller in size than the openings OA of the mesh pattern 420 inthe non-folding areas NFA1, NFA2 and NFA3.

FIG. 12 is a diagram illustrating a structure of a support substrate 460of the foldable display device 4000 according to still another exemplaryembodiment of the present disclosure.

Referring to FIG. 12 , the foldable display device 4000 according tostill another exemplary embodiment of the present disclosure includes asupport substrate 460 disposed under a display panel 400. The supportsubstrate 460 can include a plurality of opening patterns 465 formed inthe folding areas FA1 and FA2.

Referring to FIG. 12 , each of a first opening pattern 465 a formed inthe first folding area FA1 of the support substrate 460 and a secondopening pattern 465 b formed in the second folding area FA2 can have anoval-like shape having a major axis along the Y-axis direction and aconstant minor axis length. For example, each of the first openingpattern 465 a and the second opening pattern 465 b has a shape wheresemi-circles are respectively combined to both ends of a rectangularshape. Further, the first opening pattern 465 a and the second openingpattern 465 b can be spaced apart from each other at a predetermineddistance.

In the foldable display device 4000 according to still another exemplaryembodiment of the present disclosure, the first opening pattern 465 aformed in the first folding area FA1 of the support substrate 460 can beidentical in size to the second opening pattern 465 b formed in thesecond folding area FA2. Alternatively, the first opening pattern 465 aformed in the first folding area FA1 can be different in size from thesecond opening pattern 465 b formed in the second folding area FA2.Specifically, the first opening pattern 465 a formed in the firstfolding area FA1 can have a longer minor axis length than the secondopening pattern 465 b formed in the second folding area FA2.

For example, if the first folding area FA1 has a smaller radius ofcurvature than the second folding area FA2, the first opening pattern465 a in the first folding area FA1 can have a longer minor axis lengthin a folding direction (X-axis direction) than the second openingpattern 465 b in the second folding area FA2 in order for the firstfolding area FA1 to be more easily folded.

Further, in order for the first folding area FA1 to be more easilyfolded, a space between the first opening patterns 465 a in the firstfolding area FA1 can be narrower than a space between the second openingpatterns 465 b in the second folding area FA2.

Further, the sizes of the opening patterns 465 a and 465 b in each ofthe folding areas FA1 and FA2 can be adjusted so that the radius ofcurvature can increase at the edges of the folding areas FA1 and FA2.Further, stress concentrated at the folding areas FA1 and FA2 can bereduced.

FIG. 13 is a cross-sectional view of the foldable display device 4000when folded according to still another exemplary embodiment of thepresent disclosure.

Referring to FIG. 13 , when the foldable display device 4000 accordingto still another exemplary embodiment of the present disclosure isfolded, the folding areas FA1 and FA2 are folded around folding axes,respectively. Further, the folding areas FA1 and FA2 form a part of acircle or an oval. Here, the radius of curvature of the folding areasFA1 and FA2 refers to the radius of the circle or the oval formed by thefolding areas FA1 and FA2. When the folding areas FA1 and FA2 are foldedaround the folding axes, respectively, the non-folding areas NFA1, NFA2and NFA3 can overlap each other.

In the foldable display device 4000 according to still another exemplaryembodiment of the present disclosure shown in FIG. 13 , a top surfacewhere an image is displayed is defined as a display surface 1000 a, anda bottom surface of the foldable display device 4000 opposite to thedisplay surface 1000 a is defined as a rear surface 1000 b. Herein, thefolding areas FA1 and FA2 can be folded in an out-folding type in whichthe display surface 1000 a of the foldable display device 4000 is foldedto be exposed to the outside. Alternatively, the folding areas FA1 andFA2 can be folded in an in-folding type in which the display surface1000 a of the foldable display device 4000 is folded to face each other.

Referring to FIG. 13 , the first folding area FA1 can be folded inwardsso that the display surface 1000 a in the first non-folding area NFA1and the display surface 1000 a in the second non-folding area NFA2 canbe folded to face each other. Further, the second folding area FA2 canbe folded outwards so that the rear surface 1000 b in the thirdnon-folding area NFA3 and the rear surface 1000 b in the secondnon-folding area NFA2 can be folded to face each other. Further, whenthe first folding area FA1 and the second folding area FA2 are folded,the first folding area FA1 can have a smaller radius of curvature thanthe second folding area FA2.

A foldable display device according to an exemplary embodiment of thepresent disclosure includes a mesh pattern made of metal and having theplurality of openings between flexible substrates. The openings of themesh pattern increase in size from a folding area toward a non-foldingarea. Thus, the reflectivity at a pattern portion of structure thatsupports a display panel can be reduced. Therefore, it is possible tominimize the user's visual recognition of the pattern portion.

Further, heat generated from the display panel while the foldabledisplay device according to an exemplary embodiment of the presentdisclosure is driven can be easily diffused. Therefore, it is possibleto suppress the occurrence of mura in the folding area.

The exemplary embodiments of the present disclosure can also bedescribed as follows.

According to an aspect of the present disclosure, there is provided afoldable display device. The foldable display device includes a displayarea having a plurality of unit pixels and a non-display areasurrounding the display area, and a folding area defined in the displayarea and the non-display area, and non-folding areas on both sides ofthe folding area, comprising a first substrate, a second substratecorresponding to the first substrate and including the plurality of unitpixels, a thin film transistor disposed on the second substrate, anorganic light emitting diode disposed on the thin film transistor, and amesh pattern disposed between the first substrate and the secondsubstrate and having a plurality of openings, wherein openings of themesh pattern in the folding area are smaller in size than openings ofthe mesh pattern in the non-folding areas.

The foldable display device can further comprise folding boundary areasbetween the folding area and the non-folding areas, wherein the openingsof the mesh pattern in the folding area are smaller in size thanopenings of the mesh pattern in the folding boundary areas.

The openings of the mesh pattern in the folding boundary areas can besmaller in size than the openings of the mesh pattern in the non-foldingareas.

The openings of the mesh pattern can gradually increase in size from thefolding area toward the non-folding areas.

A pattern of the mesh pattern can be disposed corresponding to the sizeof each of the plurality of unit pixels.

Each of the plurality of unit pixels can include a plurality ofsub-pixels, and an opening of the mesh pattern can be disposedcorresponding to at least two of the sub-pixels.

All the openings of the mesh pattern in the folding area can have thesame size.

All the openings of the mesh pattern in the non-folding areas can havethe same size.

The mesh pattern can be greater in size than the display area andsmaller in size than the first substrate.

Openings of the mesh pattern in the non-display area can be identical insize to openings of the mesh pattern in the adjacent display area.

The folding area can include a first folding area and a second foldingarea spaced apart from the first folding area, and the first foldingarea can be an in-folding area and the second folding area is anout-folding area.

According to another aspect of the present disclosure, there is provideda foldable display device. The foldable display device that includes afolding area and a non-folding area, comprises a support substratehaving an opening pattern corresponding to the folding area, a firstsubstrate disposed on the support substrate, a second substrate disposedon the first substrate and including a thin film transistor and anorganic light emitting diode, and a mesh pattern disposed between thefirst substrate and the second substrate and having a plurality ofopenings, wherein a line width of the mesh pattern in a folding boundaryarea between the folding area and the non-folding area is smaller than aline width of the wiring line of the mesh pattern in the folding areaand greater than a line width of the wiring line of the mesh pattern inthe non-folding area.

The folding boundary area can be disposed corresponding to an edge areaof the opening pattern of the support substrate.

Openings of the mesh pattern in the folding boundary area can be greaterin size than openings of the mesh pattern in the folding area andsmaller in size than openings of the mesh pattern in the non-foldingarea.

All the openings of the mesh pattern in the folding boundary area canhave the same size.

The foldable display device further comprises an insulating layerbetween the first substrate and the second substrate, wherein theinsulating layer fully covers the mesh pattern.

Openings of the mesh pattern in the folding boundary area can graduallyincrease in size as getting farther away from the folding area.

According to yet another aspect of the present disclosure, there isprovided a foldable display device. The foldable display device furthercomprises a back plate between the support substrate and the firstsubstrate, wherein the back plate is made of a transparent material.

The folding area can include a first folding area and a second foldingarea spaced apart from the first folding area, and the first foldingarea can be an in-folding area and the second folding area is anout-folding area.

Openings of the mesh pattern in the first folding area can be identicalin size to openings of the mesh pattern in the second folding area.

Although the exemplary embodiments of the present disclosure have beendescribed in detail with reference to the accompanying drawings, thepresent disclosure is not limited thereto and can be embodied in manydifferent forms without departing from the technical concept of thepresent disclosure. Therefore, the exemplary embodiments of the presentdisclosure are provided for illustrative purposes only but not intendedto limit the technical concept of the present disclosure. The scope ofthe technical concept of the present disclosure is not limited thereto.Therefore, it should be understood that the above-described exemplaryembodiments are illustrative in all aspects and do not limit the presentdisclosure. The protective scope of the present disclosure should beconstrued based on the following claims, and all the technical conceptsin the equivalent scope thereof should be construed as falling withinthe scope of the present disclosure.

What is claimed is:
 1. A foldable display device that includes a displayarea having a plurality of unit pixels and a non-display areasurrounding the display area, and a folding area defined in the displayarea and the non-display area, and non-folding areas on sides of thefolding area, the foldable display device comprising: a first substrate;a second substrate corresponding to the first substrate and includingthe plurality of unit pixels; a thin film transistor disposed on thesecond substrate; an organic light emitting diode disposed on the thinfilm transistor; and a mesh pattern disposed between the first substrateand the second substrate, and having a plurality of openings, whereinopenings of the mesh pattern in the folding area are smaller in sizethan openings of the mesh pattern in the non-folding areas.
 2. Thefoldable display device according to claim 1, further comprising:folding boundary areas between the folding area and the non-foldingareas, wherein the openings of the mesh pattern in the folding area aresmaller in size than openings of the mesh pattern in the foldingboundary areas.
 3. The foldable display device according to claim 2,wherein the openings of the mesh pattern in the folding boundary areasare smaller in size than the openings of the mesh pattern in thenon-folding areas.
 4. The foldable display device according to claim 1,wherein the openings of the mesh pattern gradually increase in size fromthe folding area toward the non-folding areas.
 5. The foldable displaydevice according to claim 1, wherein a pattern of the mesh pattern isdisposed to correspond to the size of each of the plurality of unitpixels.
 6. The foldable display device according to claim 1, whereineach of the plurality of unit pixels includes a plurality of sub-pixels,and an opening of the mesh pattern is disposed to correspond to at leasttwo of the sub-pixels.
 7. The foldable display device according to claim1, wherein all the openings of the mesh pattern in the folding area havea same size.
 8. The foldable display device according to claim 1,wherein all the openings of the mesh pattern in the non-folding areashave a same size.
 9. The foldable display device according to claim 1,wherein the mesh pattern is greater in size than the display area, andis smaller in size than the first substrate.
 10. The foldable displaydevice according to claim 1, wherein openings of the mesh pattern in thenon-display area are identical in size to openings of the mesh patternin the adjacent display area.
 11. The foldable display device accordingto claim 1, wherein the folding area includes a first folding area and asecond folding area spaced apart from the first folding area, and thefirst folding area is an in-folding area and the second folding area isan out-folding area.
 12. A foldable display device that includes afolding area and a non-folding area, the foldable display devicecomprising: a support substrate having an opening pattern correspondingto the folding area; a first substrate disposed on the supportsubstrate; a second substrate disposed on the first substrate, andincluding a thin film transistor and an organic light emitting diode;and a mesh pattern disposed between the first substrate and the secondsubstrate, and having a plurality of openings, wherein a line width ofthe mesh pattern in a folding boundary area between the folding area andthe non-folding area is smaller than a line width of the wiring line ofthe mesh pattern in the folding area, and is greater than a line widthof the wiring line of the mesh pattern in the non-folding area.
 13. Thefoldable display device according to claim 12, wherein the foldingboundary area is disposed to correspond to an edge area of the openingpattern of the support substrate.
 14. The foldable display deviceaccording to claim 12, wherein openings of the mesh pattern in thefolding boundary area are greater in size than openings of the meshpattern in the folding area, and are smaller in size than openings ofthe mesh pattern in the non-folding area.
 15. The foldable displaydevice according to claim 14, wherein all the openings of the meshpattern in the folding boundary area have a same size.
 16. The foldabledisplay device according to claim 12, further comprising: an insulatinglayer between the first substrate and the second substrate, wherein theinsulating layer fully covers the mesh pattern.
 17. The foldable displaydevice according to claim 12, wherein openings of the mesh pattern inthe folding boundary area gradually increase in size as getting fartheraway from the folding area.
 18. The foldable display device according toclaim 12, further comprising: a back plate between the support substrateand the first substrate, wherein the back plate is made of a transparentmaterial.
 19. The foldable display device according to claim 12, whereinthe folding area includes a first folding area and a second folding areaspaced apart from the first folding area, and the first folding area isan in-folding area and the second folding area is an out-folding area.20. The foldable display device according to claim 19, wherein openingsof the mesh pattern in the first folding area are identical in size toopenings of the mesh pattern in the second folding area.